Quote Originally Posted by blacksambo View Post
If you have not changed to synthetic lubricants in the driveline then that would be a step forward. Not only will that improve mileage but these synthetics last much longer...double, triple normal fluids. And don't forget the special limited-slip fluid when you change the rear end.
I know with Royal Purple diff fluid, you do NOT have to add the LSD additive. It's formulation covers that somehow. I know confirmation of that has been posted several times on here.
Perhaps that's the case with the other top synthetics as well, but I'm not sure.